Drought Strategies for Vegetable Gardening

Drought is inevitable in California, but the last three years have been exceptionally dry. The press has concentrated on the West, but the California drought might serve as a wakeup call to all Americans about our nation’s dwindling water supply. Lack of yearly rainfall is only one factor in our current drought conditions; much of the water we use every day is actually unseen, stored underground in thousands of aquifers. We pump millions of gallons from these hidden stores each day, causing wells to go dry and land to sink, and threatening wild areas. The United States Geological Association compares aquifers to a bank account: Rainfall is our income, and the level of ground water in an aquifer is the account balance. America, then, is on a seemingly endless spending spree, systematically overdrawing our water supply each year. Click here to learn more.

When we look to the American West the scarcity of water is plainly visible. But what can we do? How can we all use our water more responsibly now to ensure a more secure future? Shrink or eliminate our lawns? Sure. Use drip irrigation? Yes. Recycle water? Of course. Plant more vegetables and fruits? Believe it or not, yes.

According to TreeHugger, a media outlet for sustainability news, the average commercial grower uses 15 gallons of water to raise one pound of lettuce, 22 gallons per pound of tomatoes, and 30 gallons for each pound of potatoes. John Jeavons, author of the best-selling How to Grow More Vegetables, has determined that using his Biointensive system, the average home gardener can use as little as 12% of the water a commercial grower uses for each pound of vegetables produced.

All my favorite culinary herbs can be grown in a few recycled wine barrels. Notice that one is a smaller one nested on top of a large one. Here Thai basil, chives, savory, tarragon, sage, French sorrel, and thyme are grouped together and watered by drip irrigation on an automatic timer that comes on twice a day for 5 minutes all summer. A bonus container of strawberries is on the same system. (Photo courtesy of Rosalind Creasy)

Saving Water in the Garden

Many homeowners, especially in arid climates, use more than half their household’s water on landscaping, so the biggest water savings can be made here. Here are some ways to cut down on water use in the garden.

Incorporate organic matter in your soil

A 3-inch layer of compost turned into your soil at a 6-inch depth (about a shovel blade depth) is estimated to increase the water holding capacity of that soil by 250%. Soils composted in this manner can provide plants with water for up to a week between watering.  The Rodale Institute has a simple equation: 1 pound of carbon (a. k. a. compost) equals 40 pounds of water retention.

Mulch heavily

Use garden compost, pine needles, aged sawdust, fall leaves, and/or straw to mulch. For annual flowers and vegetables make sure that your compost is well aged or the soil microbes will rob the soil of needed nitrogen. The looser the material the more you need to watch for slugs and snails that can hide in the mulch. Keep the mulch 6” away from the crown of annuals, shrubs, and tree trunks to prevent diseases.

Annual vegetables like peppers and zucchini use far less water when organic matter, mulch, and drip irrigation are employed. (Photo courtesy of Rosalind Creasy)

Water deeply and infrequently

Surface roots dry out faster than those at least 6” deep. Consider buying an irrigation timer, and set it to water for shorter periods of time and water a second time a few hours later, this way the water will penetrate more deeply. Most irrigation timers can be set to do this. A great tool to make sure your plants are watered properly is a soil probe. Push the probe into the soil as far as you can, 6” to a foot deep or more, remove it and look at the sample and see if it contains damp or dry soil. And use the internet to help you identify hydrophobic soil. When soil gets very dry it actually sheds water just like a dry sponge and you need to apply water slowly and let it be absorbed or most of your water will drain away.

Install a drip irrigation system

Use drip irrigation for shrub borders, fruit trees, flower beds, and vegetable gardens. Drip irrigation is dramatically more efficient than overhead sprinklers (some experts say as much as 50%). Further, it cuts down on weeds, water runoff, and fungal diseases. But planning is important. A well thought-out drip irrigation system will save many headaches. Drip systems take effort to install and close attention to work effectively. Here are a few tips based on my 30 years of drip irrigation experience:

  1. Avoid cheap irrigation “kits.” They can be unreliable. It is hard to find replacement parts for repairs and some cheap plastic tubing can expand in hot weather forcing the emitters to pop off.
  2. Instead, use professional grade in-line emitters that drip water from holes in the line rather than a solid tubing system with installed emitters.
  3. Choose “shrubblers” and micro-sprayers for annuals in containers; look for flow control so you can adjust the water pattern for changing individual plants.
  4. Install a good filter and change it every few months.
  5. Cover the tubing with mulch, not only because it looks better, but because it protects the plastic from ultraviolet light so it lasts longer.
  6. Run the system every few weeks to make sure that there are no leaks or clogs. You can have an irrigation specialist install your system or, for DIY, go to a plumbing supply store for help and parts, or seek out information online.

Deep water trees and shrubs

Deep root-watering large trees is much more efficient than most irrigation techniques as it distributes water a foot or more below the surface. Done properly a few times a summer, it eliminates surface run off and reduces erosion and evaporation. There are injection tools that attach to the hose and are inserted into the soil in 6 or 8 areas around the drip line of the shrub or tree and are run for a few hours at a time. Or use an old plastic garbage can with a few holes in the bottom. Move it to the drip line and fill it with water and let it slowly leak into the soil; when it’s empty, move it to another quadrant.

Use gray water when possible

Gray water is defined as relatively clean waste water from showers, baths, sinks, and washing machines. I keep a few plastic gallon buckets near my kitchen and bathroom sinks and put the buckets under the faucet when I’m bringing hot water to the sink or shower, and I use them when I rinse vegetables, my hands, etc.

Gray water is suitable for use in the garden because soil microbes tie up most disease organisms and toxins. When using gray water, avoid laundry soaps that contain sodium, salt compounds, and boron which can damage plants. Look for biodegradable products if you plan on using greywater. For much more information on gray water and soap brands consult Greywater Action.

Install rain barrels

Rain barrels are a natural for rainy climates, but how about in arid climates? I have found my two 75 gallon barrels quite useful. Certainly I collect rain water during our rainy season, but I also use them all year long to store gray water from the house to water my plants. For a diagram and guidelines on how to best use rainwater see the city of Berkeley’s website for information.

When grown using organic techniques and drip irrigation, home-grown tomatoes, peppers, squash, basil, and onions not only taste better, compared to large-scale agriculture, they use less than half the water. (Photo courtesy of Rosalind Creasy)

With California’s drought predicted to persist, many farmers must leave their land fallow in the state that produces more than half of the nation’s produce. We can expect the price of produce to increase dramatically in the next year. For those who choose to grow their own produce  and even those who don’t – water conservation may soon be more important than ever.

Garden and food writer, photographer and landscape designer with a passion for beautiful vegetables and ecologically sensitive gardening, Rosalind Creasy is the author of multiple books, including The Complete Book of Edible Landscaping. Throughout her more than 30-year career in horticulture, she has continued to share her knowledge of gardening and cooking by writing, lecturing nationwide, and appearing on television and radio shows. Her photographs appear frequently in numerous magazines, calendars (including Seed Saver Exchange's annual calendar) and books.

Seed Savers Exchange is a non-profit organization located in Decorah, Iowa, with a mission to conserve and promote America's culturally diverse but endangered garden and food crop heritage for future generations by collecting, growing, and sharing heirloom seeds and plants.